glacier – n. very large area of ice that moves slowly down a slope or valley or over a wide area of land

retreat – v. go away from one place to another

assume – v. think that something might be or is likely to be true, but without actual proof

reminder – n. thing that causes someone to remember something

temporary – adj. happening only for a short or limited time

pattern – n. a particular way something is repeated

impact – n. the effect something has on something else